Almost six months have passed since Sandra Lindsay, the first infected nurse in the United States, became infected with COVID-19. vaccineSince Patient 1, more than 100 million Americans have been vaccinated. In fact, as of Tuesday, at least 63.8% of adults in the United States have been vaccinated once, according to the Centers for Disease Control and Prevention (CDC).
More states and cities are fully reopening as vaccination rates rise, COVID-19 cases decline nationwide, and the CDC continues to relax restrictions. This means that life in the United States after a pandemic is slowly approaching “normal.”
But experts say it’s unclear if we’re just in a temporary rest or if the pandemic is about to reach a more permanent end. Reason?Researchers still do not know How long does immunity last? Vaccinated people and whether booster shots are needed.
The idea that coronaviruses may require booster shots is not new. Even at the dawn of a pandemic, it was possible because it is relatively common for vaccines to require booster immunity later. Tetanus, diphtheria, and whooping cough are one of the pathogens that the vaccine later requires booster immunity.
Recent studies on Pfizer’s SARS-CoV-2 vaccine have shown that it provides at least sustained immunity. 6 monthsIf your immunity weakens after a period of time, you may need a booster.
However, there are other factors that influence the need for booster shots besides the duration of immunity. Mutations also change the equation.
Amesh Adalja, a senior scholar at the Johns Hopkins Center, said salon infection specialists are monitoring whether people who are completely vaccinated are re-infected. If so, how serious are their cases?
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“For me, that’s the threshold you use,” Adalja said. “That is, follow vaccinated people to look for breakthrough infections, and more serious breakthrough infections at certain times. Do you want to make sure they are happening? At that point you can decide if you need them. “
Dr. Charles Chiu, a professor of infectious diseases at the University of California, San Francisco, agreed with this threshold concept. But Chiu said it was too early to decide if a booster was needed, partly because not everyone in the United States is vaccinated.
“If we start seeing an increase in the number of infected people in the vaccinated population, we know we need boosters, but at this point, a significant portion of the population is unvaccinated, so we’ll evaluate it. “It’s difficult,” Chiu said. “For example, once you have a basic population immunity, you can continue to monitor your infection and monitor your infection to see if you need a booster. [COVID-19] Screening. “
As Chiu hinted, there is debate about whether booster shots are needed. “It’s too early to tell,” Chiu said, but advised to prepare for that possibility.
In addition to boosters, seasonal vaccination is a common practice for vaccines. Influenza vaccinations are provided annually and are updated regularly to reflect the flu season virus. Children who receive the MMR vaccine to prevent measles, mumps, and rubella receive the first vaccination between the ages of 12 and 15 months and the second vaccination between the ages of 4 and 6. Not long ago Salon interviewed with an infectious disease expert, Chiu was also included, and I speculated that the COVID-19 vaccine could be a seasonal vaccine.
Fortunately, the effect is Multiple COVID-19 vaccines It surprised many of the sites and exceeded expectations. However, immunity to COVID-19 does not seem to last forever.
“We know that vaccine-induced immunity declines over time. The question is how quickly it declines, but in the end it can decline in a way that requires a booster. There is sex, “added Chiu. He pointed out that there is another looming reason why boosters may be needed. It’s a mutation.
“The emergence of mutants that can affect the effectiveness of the vaccine in various ways” may require boosters, Chiu said.
Adalja also said he thinks it’s too early to assert.
“Especially premature … It takes time to study fully vaccinated people to see if they have a breakthrough infection,” Adalja said. “Based on this data from the general population, I don’t think it will be in the short term. It can be different for immunocompromised patients and those at high risk.”
However, not all infectious disease experts agree. Infectious disease doctor Monica Gandhi, a professor at the University of California, San Francisco, told the salon that she didn’t think she needed a booster. There are four main reasons for this. First, Gandhi pointed out. For one study The results showed that mild COVID-19-infected individuals showed a “good T cell response.” This means that the immune system has a strong memory.
The immune system produces both B and T cells in response to infection. B cells produce antibodies, and T cells specifically attack and kill pathogens. As Gandhi explained, T-cell immunity persists for a long time after vaccination against other infections such as measles, mumps, rubella, whooping cough, and diphtheria.
Many scientists have found that T cells are immune to SARS-CoV-2. Durable (Meaning sustainability) Same as SARS 17 years ago.Gandhi pointed Individual studies Twelve people who received two Pfizer / BioNTech vaccinations have shown that the concentration of lymph node memory B cell storage increases over time. You can prevent the original SARS-CoV-2.
But what about variants?
“Antibody levels may be reduced for certain mutants, but the T cells produced by the vaccine produce multiple” epitopes “… and about 100 across the peplomer protein. Vaccinations help individual T cells fight infections, “said Gandhi.
“And even if you have mutants with 13 mutations, such as delta mutants with many mutations, you will get a large lineup of T cells that fight some of those mutants. The cellular response from the vaccine will work against them. “
Hopefully the new variant will be a nonsensical issue. Chiu said it is possible to prevent the emergence of new variants, but the possibility depends on the global vaccination.
“One thing to keep in mind is that the rest of the world is still barely immune and the rest of the world isn’t actually vaccinated,” Chiu said. The reason for the emergence of these variants is that there is a persistent infection, so we will continue to observe the emergence of these variants until we can control the global pandemic. “
Chiu emphasized that this is a major concern as it can affect the need for booster shots.
In particular, booster shots have already been administered in some countries. According to the Associated Press United Arab Emirates Provides boosters to those who receive the Sinopharm vaccine. Adalja said this does not necessarily predict what will happen in the United States.
“China National Pharmaceutical has not announced Phase 3 Because it’s clinical data, we don’t fully understand how effective it is, “said Adalja.” But what we know is that both Sinovac and Sinopharm are Moderna, Pfizer, It doesn’t seem to work as well as AstraZeneca, Johnson. & Johnson — The vaccine may have some specific problems. “
